/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.boonya.spark.examples.sql.streaming;

import org.apache.kafka.common.security.auth.SecurityProtocol;
import org.apache.spark.api.java.function.FlatMapFunction;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Encoders;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.sql.streaming.StreamingQuery;

import java.util.Arrays;

/**
 * Consumes messages from one or more topics in Kafka and does wordcount.
 * Usage: JavaStructuredKerberizedKafkaWordCount <bootstrap-servers> <subscribe-type> <topics>
 * <bootstrap-servers> The Kafka "bootstrap.servers" configuration. A
 * comma-separated list of host:port.
 * <subscribe-type> There are three kinds of type, i.e. 'assign', 'subscribe',
 * 'subscribePattern'.
 * |- <assign> Specific TopicPartitions to consume. Json string
 * |  {"topicA":[0,1],"topicB":[2,4]}.
 * |- <subscribe> The topic list to subscribe. A comma-separated list of
 * |  topics.
 * |- <subscribePattern> The pattern used to subscribe to topic(s).
 * |  Java regex string.
 * |- Only one of "assign, "subscribe" or "subscribePattern" options can be
 * |  specified for Kafka source.
 * <topics> Different value format depends on the value of 'subscribe-type'.
 * <p>
 * Example:
 * Yarn client:
 * $ bin/run-order --files ${jaas_path}/kafka_jaas.conf,${keytab_path}/kafka.service.keytab \
 * --driver-java-options "-Djava.security.auth.login.config=${path}/kafka_driver_jaas.conf" \
 * --conf \
 * "spark.executor.extraJavaOptions=-Djava.security.auth.login.config=./kafka_jaas.conf" \
 * --master yarn
 * sql.streaming.JavaStructuredKerberizedKafkaWordCount broker1-host:port,broker2-host:port \
 * subscribe topic1,topic2
 * Yarn cluster:
 * $ bin/run-order --files \
 * ${jaas_path}/kafka_jaas.conf,${keytab_path}/kafka.service.keytab,${krb5_path}/krb5.conf \
 * --driver-java-options \
 * "-Djava.security.auth.login.config=./kafka_jaas.conf \
 * -Djava.security.krb5.conf=./krb5.conf" \
 * --conf \
 * "spark.executor.extraJavaOptions=-Djava.security.auth.login.config=./kafka_jaas.conf" \
 * --master yarn --deploy-mode cluster \
 * sql.streaming.JavaStructuredKerberizedKafkaWordCount broker1-host:port,broker2-host:port \
 * subscribe topic1,topic2
 * <p>
 * kafka_jaas.conf can manually create, template as:
 * KafkaClient {
 * com.sun.security.auth.module.Krb5LoginModule required
 * keyTab="./kafka.service.keytab"
 * useKeyTab=true
 * storeKey=true
 * useTicketCache=false
 * serviceName="kafka"
 * principal="kafka/host@EXAMPLE.COM";
 * };
 * kafka_driver_jaas.conf (used by yarn client) and kafka_jaas.conf are basically the same
 * except for some differences at 'keyTab'. In kafka_driver_jaas.conf, 'keyTab' should be
 * "${keytab_path}/kafka.service.keytab".
 * In addition, for IBM JVMs, please use 'com.ibm.security.auth.module.Krb5LoginModule'
 * instead of 'com.sun.security.auth.module.Krb5LoginModule'.
 * <p>
 * Note that this order uses SASL_PLAINTEXT for simplicity; however,
 * SASL_PLAINTEXT has no SSL encryption and likely be less secure. Please consider
 * using SASL_SSL in production.
 */
public final class JavaStructuredKerberizedKafkaWordCount {
    public static void main(String[] args) throws Exception {
        if (args.length < 3) {
            System.err.println("Usage: JavaStructuredKerberizedKafkaWordCount <bootstrap-servers> " +
                "<subscribe-type> <topics>");
            System.exit(1);
        }

        String bootstrapServers = args[0];
        String subscribeType = args[1];
        String topics = args[2];

        SparkSession spark = SparkSession
            .builder()
            .appName("JavaStructuredKerberizedKafkaWordCount")
            .getOrCreate();

        // Create DataSet representing the stream of input lines from kafka
        Dataset<String> lines = spark
            .readStream()
            .format("kafka")
            .option("kafka.bootstrap.servers", bootstrapServers)
            .option(subscribeType, topics)
            .option("kafka.security.protocol", SecurityProtocol.SASL_PLAINTEXT.name)
            .load()
            .selectExpr("CAST(value AS STRING)")
            .as(Encoders.STRING());

        // Generate running word count
        Dataset<Row> wordCounts = lines.flatMap(
            (FlatMapFunction<String, String>) x -> Arrays.asList(x.split(" ")).iterator(),
            Encoders.STRING()).groupBy("value").count();

        // Start running the query that prints the running counts to the console
        StreamingQuery query = wordCounts.writeStream()
            .outputMode("complete")
            .format("console")
            .start();

        query.awaitTermination();
    }
}
